回热式有机朗肯循环系统热力性能

膨胀机和工质泵作为有机朗肯循环系统的重要动力部件,在不同的热源温度下,合适的膨胀机及工质泵转速能够有效提高有机朗肯循环(organic Rankine cycle, ORC)系统的热效率。基于回热式ORC系统的热力学分析,选用1,1,1,3,3-五氟丙烷(R245fa)为工质研究了膨胀机转速、工质泵转速以及热源温度对系统性能的影响。结果表明:膨胀机转速的增加使得工质质量流量、蒸发器换热量、膨胀机输出功和系统净输出功有所上升,而蒸发压力和热效率下降;工质泵转速的增加使得工质质量流量、蒸发压力、蒸发器换热量及系统净输出功升高,系统热效率先增加后降低;热源温度的升高导致蒸发压力下降,工质质量流量、蒸发器换热量、膨胀机输出功、净输出功及热效率均随之增加。

Thermal performance analysis of Organic Rankine Cycle system with regenerator

Expander and working fluid pump are important power components of ORC system. Under different heat source temperature, appropriate speed of expander and working fluid pump can effectively improve the thermal efficiency of Organic Rankine Cycle system. Based on the thermodynamic analysis of the ORC system with regenerator, R245fa was selected as the working fluid to study the influence of expander speed, working fluid pump speed and heat source temperature on system performance. The results show that the mass flow of working fluid, the heat exchange in evaporator, the output work of the expander and the net output work of the system are increased with the increase of the expander speed, while the evaporating pressure and thermal efficiency are decreased. The increase of working fluid pump speed will increase the mass flow rate of working fluid, evaporating pressure, evaporator heat exchange and the net output work of the system, and the thermal efficiency of the system will increase first and then decrease. The increase of the heat source temperature will lead to the decrease of the evaporating pressure, and the mass flow of the working fluid, the heat exchange in the evaporator, the output work of the expander, the net output work and the thermal efficiency will increase accordingly.